1. Field of the Invention
The present invention relates to a steering device for front and rear wheels, and more particularly to a steering device for steering front and rear wheels through rack-and-pinion steering gear boxes disposed in front and rear positions on a motor vehicle frame.
2. Description of the Relevant Art
Various steering devices for steering front and rear wheels at the same time have been proposed in the art. One type of such steering device is disclosed in U.S. Pat. Nos. 4,467,885 and 4,538,824, for example. According to the disclosed steering devices, rack-and-pinion steering gear boxes for front and rear wheels are located in front and rear positions, respectively, on a motor vehicle frame, and a linkage shaft is employed to connect the shaft of a rotation output pinion in the front wheel steering gear to the shaft of a rotation input pinion in the rear wheel steering gear.
With the above conventional steering device, however, the distance between the front and rear steering gear boxes tends to vary from vehicle to vehicle due to manufacturing or assembling errors of shafts such as the pinion shafts of the steering gear boxes and the linkage shaft between the steering gear boxes, and such shafts on completed vehicles are liable to move axially under external stresses, resulting in a change in the distance between the front and rear steering gear boxes. It has been customary practice in the past to couple the shaft members to joint members therebetween through splines for thereby absorbing changes in the box-to-box distance in the axial direction of the shaft members.
The present invention has been made to solve the above problem in a different approach than the above customary solution.